cos20*cos70-sin20*sin70
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cos20*cos70-sin20*sin70
cos20°*cos70°-sin20°*sin70°=
1+tan15/1-tan15°=
sin72°*cos18°+cos72°*sin18°=
tan12°+tan33/1-tan12°*tan33°=
已知cosθ=—3/5 θ∈(π/2,π),求sin(θ+π/3)的值
sin15°*cos15°=
cos²π/8—sin²π/8=
tan22.5°/1—tan²22.5°=
2cos²22.5°—1=
sin(—7π/12)=
cos(—61π/12)=
tan35π/12=
已知cosa/8=—4/5,8π
大神们顺便把过程也附上吧.......
cos20°*cos70°-sin20°*sin70°=
1+tan15/1-tan15°=
sin72°*cos18°+cos72°*sin18°=
tan12°+tan33/1-tan12°*tan33°=
已知cosθ=—3/5 θ∈(π/2,π),求sin(θ+π/3)的值
sin15°*cos15°=
cos²π/8—sin²π/8=
tan22.5°/1—tan²22.5°=
2cos²22.5°—1=
sin(—7π/12)=
cos(—61π/12)=
tan35π/12=
已知cosa/8=—4/5,8π
大神们顺便把过程也附上吧.......
cos20°*cos70°-sin20°*sin70°=cos(20°+70°)=cos(90°)=0
已知sinx=—3/5,x是第四象限角,求sin(π/4—x)cos(π/4+x),tan(x—π/4)的值
cosx=4/5 (因为x是第四象限)
sin(π/4—x)
=sin π/4 cosx-cosπ/4 sinx
=(根号2/2)(4/5+3/5)
=7根号2/10
cos(π/4+x)
=cosπ/4 cosx -sinπ/4 sinx
=(根号2/2)(4/5+3/5)
=7根号2/10
tanx=sinx/cosx=-3/4
tan(x—π/4)
=(tan x- tanπ/4 )/(1+tanx tanπ/4)
=(-3/4-1)/(1-3/4)
=-7
已知sinx=—3/5,x是第四象限角,求sin(π/4—x)cos(π/4+x),tan(x—π/4)的值
cosx=4/5 (因为x是第四象限)
sin(π/4—x)
=sin π/4 cosx-cosπ/4 sinx
=(根号2/2)(4/5+3/5)
=7根号2/10
cos(π/4+x)
=cosπ/4 cosx -sinπ/4 sinx
=(根号2/2)(4/5+3/5)
=7根号2/10
tanx=sinx/cosx=-3/4
tan(x—π/4)
=(tan x- tanπ/4 )/(1+tanx tanπ/4)
=(-3/4-1)/(1-3/4)
=-7
三角函数化简题 帮帮忙 2sin20°+2cos*2 5°+(cos70°sin10°)/sin70°
数学函数化简题2cos10°-sin20°/cos20°=?sin40°+2cos70°/sin50°=?
cos70度,sin70度咋算的?
(sin20*sin10)/(cos20*cos10)
sin20*cos40+sin40*cos20
为什么根号(sin20-cos20)^2=cos20-sin20
根号[(3/sin20')-(1/cos20')],
求值:cos20°sin20°
sin70°-cos70°/sin70°+cos70°=多少啊
1/cos20°-根号3/sin20°
1.(2cos10-sin20)/cos20=______
化简求解释清楚 2sin20 cos20